1. Field of the Invention
This invention relates to keyboards having both data entry and pointer control functions.
2. Description of Related Art
Keyboards with Pointer Function
Use of a conventional keyboard and a discrete computer mouse in order to enter typing and pointing information, respectively, into a computer require physical disruption that may significantly reduce a user's productivity. For example, typing on a keyboard and pointing with a mouse require the user to frequently move the user's hands back and forth between the keyboard and the mouse. Moreover, a conventional computer mouse is an external device that requires an additional flat surface to operate.
To reduce hand movement and minimize space requirement, a number of data input devices with combined keyboard/pointer function have been designed and implemented. These designs typically have a pointing device, such as a trackball, a touchpad, or a track point, mounted on a keyboard and are commonly used in lap-top computers. All these devices require complicated hardware and software designs that result in increased cost and reduced reliability.
There are a number of other designs that integrate the pointer function into one or more pre-assigned keys on the keyboard.
U.S. Pat. No. 5,278,557, which is herein incorporated by reference, discloses a keyboard design in which the keyboard contains a cursor movement control key. The cursor movement control key is force-sensitive and can be used in a manner similar to a joystick.
U.S. Pat. No. 6,052,071, which is herein incorporated by reference, discloses a keyboard with keys for moving a cursor wherein the cursor movement is controlled by pressing a plurality of keys in a skewed or sideways manner. This operation, however, is difficult to perform when more than one of the plurality of depressable keys need to be pressed simultaneously in a common skewed direction (col. 3, lines 40–41). Furthermore, when two or more keys the screen, user's hand position is awkward for most basic upward/downward movements.
U.S. Pat. No. 6,100,875, which is herein incorporated by reference, discloses yet another keyboard pointing device in which the direction of the pointer movement is controlled by designated “mouse keys” in a manner similar to the cursor keys on a standard keyboard, and the speed of the pointer movement is controlled by intervals between keystrokes. However, since each direction of the pointer movement is controlled by a designated “mouse key”, it is difficult to move the pointer to the desired direction without actually looking at the keyboard to identify the “mouse key” that controls the movement to that direction.
Flexible Keyboard
The miniaturization of the keyboard has been another focus in the research and development of data input devices, especially in the case of portable electronic devices such as lap-top computers. Although individual keys used in a standard keyboard can be reduced in size, such size reduction often creates user difficulties in comfort and efficiency in operation. Therefore, instead of reducing the size of the individual keys, a lap-top keyboard usually has fewer keys than a standard keyboard and certain keys are rearranged from their normal position to satisfy the sizing constraint. Such modifications can result in excessive motion and typing errors and can sacrifice available options associated with the missing conventional keys.
An alternative to the hard-to-use miniature keyboard is a full size keyboard that can be carried around with a lap-top computer. A number of flexible or foldable keyboards are designed for this purpose.
U.S. Pat. No. 5,141,343, which is herein incorporated by reference, discloses a keyboard that can be compacted, protracted and adjusted to vary its size and the spacing between the keys thereof.
U.S. Pat. No. 5,220,521, which is herein incorporated by reference, discloses a keyboard that is molded from a flexible material and can be rolled into a cylinder for transport and storage.
U.S. Pat. No. 5,459,461, which is herein incorporated by reference, discloses an inflatable keyboard that can be distorted from its functional shape to permit storage in a small compartment. This feature is also integrated into U.S. Pat. No. 6,052,071 to disclose an inflatable keyboard with keys for moving cursor.
Keyboard Circuitry
Conventional keyboard circuit designs utilize a column-row matrix of conductors and key controlled switches, each adapted to feed into the computer a signal representing a particular number or character, or to deliver a predetermined command for commencing a desired operation. When a key is pressed, the corresponding switch provides continuity between the column and row conductors associated therewith. In operation, enabling signals from the data processing system may be sequentially coupled to each column (or row) conductor for scanning the keyboard for depressed keys. A depressed key is sensed when the enabling signal from the depressed key's column (or row) conductor is present on the depressed key's row (or column) conductor. To distinguish between a real signal and an aberrant current fluctuation, the scan is repeated hundreds of times each second. Only signals detected for two or more scans are acted upon by the processor. Specific controlling circuits, such as those disclosed in the U.S. Pat. No. 3,932,838 and U.S. Pat. No. 3,932,866, which are herein incorporated by reference, were also designed to prevent development of fallacious signals by bouncing or chattering of the keyboard switch contacts.
Standard 104-key keyboards normally use 8 bit micro-controllers and two 8 bit ports as the column driver and one 8 bit port as the row sense input to form a 13×8 matrix. Depending on the wiring layout, the keyboard may also use two 8 bit ports as the column driver and two 8 bit ports as the row sense input, and form a more symmetric 11×10 matrix. If more keys are required in an application, a larger matrix will be needed. The complexity of the scanning circuit IC and wiring will increase accordingly which, in turn, will raise the cost of manufacture of the keyboard.